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South Asian High and Asian-Pacific-American climate Teleconnection

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Advances in Atmospheric Sciences 2005年第6期22卷 915-923页

作者：张培群 Song YANG Vernon E. KOUSKY National climate center China Meteorological Administration Beijing 100029 noaa＇s climate prediction center Camp Springs Maryland

Growing evidence indicates that the Asian monsoon plays an important role in affecting the weather and climate outside of Asia. However, this active role of the monsoon has not been demonstrated as thoroughly as has the variability of the monsoon caused by various impacting factors such as sea surface temperature and land surface. This study investigates the relationship between the Asian monsoon and the climate anomalies in the Asian-Pacific-American （APA） sector. A hypothesis is tested that the variability of the upper-tropospheric South Asian high （SAH）, which is closely associated with the overall heating of the large-scale Asian monsoon, is linked to changes in the subtropical western Pacific high （SWPH）, the midPacific trough, and the Mexican high. The changes in these circulation systems cause variability in surface temperature and precipitation in the APA region. A stronger SAH is accompanied by a stronger and more extensive SWPH. The enlargement of the SWPH weakens the mid-Pacific trough. As a result, the southern portion of the Mexican high becomes stronger. These changes are associated with changes in atmospheric teleconnections, precipitation, and surface temperature throughout the APA region. When the SAH is stronger, precipitation increases in southern Asia, decreases over the Pacific Ocean, and increases over the Central America. Precipitation also increases over Australia and central Africa and decreases in the Mediterranean region. While the signals in surface temperature are weak over the tropical land portion, they are apparent in the mid latitudes and over the eastern Pacific Ocean.

关键词： South Asian high subtropical western Pacific high mid-Pacific trough Mexican high Asian-Pacific-American climate

Simulation and Projection of the Western Pacific Subtropical High in CMIP5 Models

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Journal of Meteorological Research 2014年第3期28卷 327-340页

作者：刘芸芸李维京左金清 HU Zeng-Zhen Laboratory for climate Studies National Climate Center China Meteorological Administration climate prediction center NCEP/NWS/NOAA College Park 20740 USA

This work examined the performance of 26 coupled climate models participating in the Coupled Model Intercomparison Project Phase 5 （CMIP5） in the simulation of the present-day temporal variability and spatial pattern of the western Pacifi c subtropical high （WPSH）. The results show that most models are able to capture the spatial distribution and variability of the 500-hPa geopotential height and zonal wind fi elds in the western subtropical Pacifi c, but with underestimated mean intensity of the WPSH. The underestimation may be associated with the cold bias of sea surface temperature in the tropical Indian and western Pacifi c oceans in the models. To eliminate the impact of the climatology biases, the climatology of these models is replaced by that of the NCEP/NCAR reanalysis in the verifi cation, and the models reproduce the WPSH’s enhancement and westward extension after the late 1970s. According to assessment of the simulated WPSH indices, it is found that some models （CNRM-CM5, FGOALS-g2, FIO-ESM, MIROC-ESM, and MPI-ESM-P） are better than others in simulating WPSH. Then, the ensemble mean of these better models is used to pro ject the future changes of WPSH under three representative concentration pathway scenarios （RCP8.5, RCP4.5, and RCP2.6）. The WPSH enlarges, strengthens, and extends westward under all the scenarios, with the largest linear growth trend projected in RCP8.5, smallest in RCP2.6, and in between in RCP4.5;while the ridge line of WPSH shows no obvious long-term trend. These results may have implications for the attribution and prediction of climate variations and changes in East Asia.

关键词： western Pacifi c subtropical high (WPSH) CMIP5

A High Resolution Nonhydrostatic Tropical Atmospheric Model and Its Performance

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Advances in Atmospheric Sciences 2005年第1期22卷 30-38页

作者：沈学顺 Akimasa SUMI center for Numerical prediction Research center for climate System Research

A high resolution nonhydrostatic tropical atmospheric model is developed by using a ready-made regional atmospheric modeling system. The motivation is to investigate the convective activities associated with the tropical intraseasonal oscillation (ISO) through a cloud resolving calculation. Due to limitations in computing resources, a

关键词： high resolution nonhydrostatic model intraseasonal oscillation microphysics convection

Subseasonal features of the Asian summer monsoon in the NCEP climate forecast system

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Acta Oceanologica Sinica 2008年第3期27卷 88-103页

作者： Song YANG WEN Min R Wayne HIGGINS noaa＇s climate prediction center Camp Springs Maryland 20746 USA Chinese Academy of Meteorological Sciences Beijing 100081 China

The operational climate forecast system （CFS） of the US National centers for Environmental prediction provides climate predictions over the world, and CFS products are becoming an important source of information for regional climate predictions in many Asian countries where monsoon climate dominates. Recent studies have shown that, on monthly-to-seasonal time-scales, the CFS is highly skillful in simulating and predicting the variability of the Asian monsoon. The higher-frequency variability of the Asian summer monsoon in the CFS is analyzed, using output from a version with a spectral triangular truncation of 126 waves in horizontal and 64 sigma layers in vertical, focusing on synoptic, quasi-biweekly, and intraseasonal time-scales. The onset processes of different regional monsoon components were investigated within Asia. Although the CFS generally overestimates variability of monsoon on these time-scales, it successfully captures many major features of the variance patterns, especially for the synoptic timescale. The CFS also captures the timing of summer monsoon onsets over India and the Indo-China Peninsula. However, it encounters difficulties in simulating the onset of the South China Sea monsoon. The success and failure of the CFS in simulating the onset of monsoon precipitation can also be seen from the associated features of simulated atmospheric circulation processes. Overall, the CFS is capable of simulating the synoptic-to-intraseasonal variability of the Asian summer monsoon with skills. As for seasonal-tointerannual time-scales shown previously, the model is expected to possess a potential for skillful predictions of the high-frequency variability of the Asian monsoon.

关键词： Asian summer monsoon onset evolution synoptic-to-intraseasonal variability NCEP climate prediction system

Roles of Multi-Scale Disturbances over the Tropical North Pacific in the Turnabout of 1997-98 El Nino

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Advances in Atmospheric Sciences 2007年第4期24卷 581-590页

作者：张祖强张人禾 Song YANG Laboratory for climate Studies National Climate Center China Meteorological Administration Beijing 100081 Chinese Academy of Meteorological Sciences China Meteorological Administration Beijing 100081 noaa climate prediction center Camp Springs MD 20746 U.S.A

The space-time features of major vorticity disturbances over the western North Pacific during the 1997-98 El Nino ranked as one of the strongest events on record was investigated in this study. We distinguished the different roles that these disturbances had on different timescales in causing the reversal or turnabout of the El Nino event. Remarkable differences in the various disturbances of synoptic, intraseasonal, and interannual timescales were found in the time evolution, propagation, and in their contributions to the changes in nearequatorial zonal flow, which was crucial to the demise of the warm sea surface temperature anomalies in the central-eastern Pacific. It is hypothesized that the westward-traveling synoptic and intraseasonal oscillations in the western North Pacific might be considered as a self-provided negative feedback from the El Nino and played an additional role in its reversal in comparison with other interannual internal and external forcings. In this case, the off-equatorial synoptic and intraseaonal fluctuations served as a stochastic forcing for the tropical ocean and gave rise to the aperiodicity or irregularity of the El Nino-Southern Oscillation.

关键词： intraseasonal oscillation ENSO Kelvin wave western North Pacific

Impacts of Land Process on the Onset and Evolution of Asian Summer Monsoon in the NCEP climate Forecast System

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Advances in Atmospheric Sciences 2011年第6期28卷 1301-1317页

作者： Song YANG 温敏 Rongqian YANG Wayne HIGGINS 张人禾 noaa ＇s climate prediction center Camp Springs Maryland 20746 State Key Laboratory of Severe Weather Chinese Academy of Meteorological Sciences Beijing 100081 noaa＇s Environmental Modeling center Camp Springs Maryland 20746

Impacts of land models and initial land conditions （ICs） on the Asian summer monsoon, especially its onset, were investigated using the NCEP climate Forecast System （CFS）. Two land models, the Oregon State University （OSU） land model and the NCEP, OSU, Air Force, and Hydrologic Research Laboratory （Noah） land model, were used to get parallel experiments NCEP/Department of Energy （DOE） Global Reanalysis 2 System （GLDAS）. The experiments also used land ICs from the （GR2） and the Global Land Data Assimilation Previous studies have demonstrated that, a systematic weak bias appears in the modeled monsoon, and this bias may be related to a cold bias over the Asian land mass. Results of the current study show that replacement of the OSU land model by the Noah land model improved the model＇s cold bias and produced improved monsoon precipitation and circulation patterns. The CFS predicted monsoon with greater proficiency in E1 Nifio years, compared to La Nifia years model in monsoon predictions for individual years. and the Noah model performed better than the OSU These improvements occurred not only in relation to monsoon onset in late spring but also to monsoon intensity in summer. Our analysis of the monsoon features over the India peninsula, the Indo-China peninsula, and the South Chinese Sea indicates different degrees of improvement. Furthermore, a change in the land models led to more remarkable improvement in monsoon prediction than did a change from the GR2 land ICs to the GLDAS land ICs.

关键词： Asian summer monsoon NCEP climate Forecast System land models land initial conditions

The 2022 Extreme Heatwave in Shanghai,Lower Reaches of the Yangtze River Valley:Combined Influences of Multiscale Variabilities

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Advances in Atmospheric Sciences 2024年第4期41卷 593-607页

作者： Ping LIANG Zhiqi ZHANG Yihui DING Zeng-Zhen HU Qi CHEN Key Laboratory of Cities’Mitigation and Adaptation to climate Change in Shanghai Shanghai Regional Climate CenterChina Meteorological AdministrationShanghai 200030China National climate center China Meteorological AdministrationBeijing 100081China climate prediction center NCEP/NWS/NOAACollege ParkMD 20740USA

In the summer of 2022,China(especially the Yangtze River Valley,YRV)suffered its strongest heatwave(HW)event since *** this study,we examined the influences of multiscale variabilities on the 2022 extreme HW in the lower reaches of the YRV,focusing on the city of *** found that about 1/3 of the 2022 HW days in Shanghai can be attributed to the long-term warming trend of global *** mid-summer of 2022,an enhanced western Pacific subtropical high(WPSH)and anomalous double blockings over the Ural Mountains and Sea of Okhotsk,respectively,were associated with the persistently anomalous high pressure over the YRV,leading to the extreme *** Pacific Decadal Oscillation played a major role in the anomalous blocking pattern associated with the HW at the decadal time ***,the positive phase of the Atlantic Multidecadal Oscillation may have contributed to regulating the formation of the double-blocking *** warming of both the warm pool of the western Pacific and tropical North Atlantic at the interannual time scale may also have favored the persistency of the double blocking and the anomalously strong *** the subseasonal time scale,the anomalously frequent phases 2-5 of the canonical northward propagating variability of boreal summer intraseasonal oscillation associated with the anomalous propagation of a weak Madden-Julian Oscillation suppressed the convection over the YRV and also contributed to the ***,the 2022 extreme HW originated from multiscale forcing including both the climate warming trend and air-sea interaction at multiple time scales.

关键词： extreme heatwave multiscale variability air-sea interaction warming trend Yangtze River Valley Shanghai

Evolution of the 2015/16 El Nio and historical perspective since 1979

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Science China Earth Sciences 2017年第9期60卷 1572-1588页

作者： Yan XUE Arun KUMAR climate prediction center National Centers for Environmental Prediction National Weather Service National Oceanic and Atmospheric Administration College Park MD 20740 USA

The 2015/16 El Nio developed from weak warm conditions in late 2014 and NINO3.4 reached 3℃ in November 2015. We describe the characteristics of the evolution of the 2015/16 El Nio using various data sets including SST, surface winds,outgoing longwave radiation and subsurface temperature from an ensemble operational ocean reanalyses, and place this event in the context of historical ENSO events since 1979. One salient feature about the 2015/16 El Nio was a large number of westerly wind bursts and downwelling oceanic Kelvin waves(DWKVs). Four DWKVs were observed in April-November 2015 that initiated and enhanced the eastern-central Pacific warming. Eastward zonal current anomalies associated with DWKVs advected the warm pool water eastward in spring/summer. An upwelling Kelvin wave(UWKV) emerged in early November 2015 leading to a rapid decline of the event. Another outstanding feature was that NINO4 reached a historical high(1.7℃), which was 1℃(0.8℃) higher than that of the 1982/83(1997/98) El Nio . Although NINO3 was comparable to that of the 1982/83 and 1997/98 El Nio , NINO1+2 was much weaker. Consistently, enhanced convection was displaced 20 degree westward, and the maximum D20 anomaly was about 1/3.1/2 of that in 1997 and 1982 near the west coast of South America.

关键词： ENSO Sea surface temperature Westerly wind bursts Ocean Kelvin waves Thermocline variability Ocean reanalysis

Time-Frequency Characteristics of the Relationships Between Tropical Indo-Pacific SSTs

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Advances in Atmospheric Sciences 2007年第3期24卷 343-359页

作者： Song YANG 丁晓利郑大伟 Soo-Hyun YOO noaa ＇s climate prediction center 5200 Auth Road Camp Springs MD 20746 USA Department of Land Surveying and Geo-Informatics Hong Kong Polytechnic University center for Astrogeodynamics Research Shanghai Astronomical Observatory Chinese Academy of Sciences Shanghai 200030 RSIS/climate prediction center 5200 Auth Road Camp Springs MD 20746 USA

In this study, several advanced analysis methods are applied to understand the relationships between the Nino-3.4 sea surface temperatures （SST） and the SSTs related to the tropical Indian Ocean Dipole （IOD）. By analyzing a long data record, the authors focus on the time-frequency characteristics of these relationships, and of the structure of IOD. They also focus on the seasonal dependence of those characteristics in both time and frequency domains. Among the Nino-3.4 SST, IOD, and SSTs over the tropical western Indian Ocean （WIO） and eastern Indian Ocean （EIO）, the WIO SST has the strongest annual and semiannual oscillations. While the Nino-3.4 SST has large inter-annual variability that is only second to its annual variability, the IOD is characterized by the largest semiannual oscillation, which is even stronger than its annual oscillation. The IOD is strongly and stably related to the EIO SST in a wide range of frequency bands and in all seasons. However, it is less significantly related to the WIO SST in the boreal winter and spring. There exists a generally weak and unstable relationship between the WIO and EIO SSTs, especially in the biennial and higher frequency bands. The relationship is especially weak in summer and fall, when IOD is apparent, but appears highly positive in winter and spring, when the IOD is unimportantly weak and even disappears. This feature reflects a caution in the definition and application of IOD. The Nino-3.4 SST has a strong positive relationship with the WIO SST in all seasons, mainly in the biennial and longer frequency bands. However, it shows no significant relationship with the EIO SST in summer and fall, and with IOD in winter and spring.

关键词： Indian Ocean dipole ENSO time-frequency relationship coherence analysis